stalagmites in thien cung cave in halong bay in quang ninh province, vietnam. amazing beauty of dolomite cave

asia bay beautiful cave cavern cliff cung dong dramatic excursion formation geological geology glow grotto halong hanoi heritage indochina island landmark landscape limestone long mountain natural nature non outdoors picturesque quang rock scenery sea seascape southeast stalactite stalagmite stone tourism tranquil travel tunnel unesco urban vietnam view water world